declination vs slope

declination and slope both are nouns.

Word	Noun	Adjective	Verb	Adverb
declination	Yes	No	No	No
slope	Yes	No	Yes	No

As nouns, slope is a hypernym of declination; that is, slope is a word with a broader meaning than declination:

Other hypernyms of declination include incline, side.

declination (noun)	slope (noun)
a polite refusal of an invitation	the property possessed by a line or surface that departs from the horizontal
(astronomy) the angular distance of a celestial body north or to the south of the celestial equator; expressed in degrees; used with right ascension to specify positions on the celestial sphere	an elevated geological formation
a downward slope or bend
a condition inferior to an earlier condition; a gradual falling off from a better state; decline

declination (verb)	slope (verb)
	be at an angle